1. Field of the Invention
The present invention relates to the purification of methyl tertiary butyl ether (MTBE) and especially to the separation of minor amounts of close boiling oxygenated impurities therefrom by contacting the impure MTBE with a large pore zeolite such as 13x zeolite or zeolite Y.
2. Description of the Prior Art
Generally MTBE as produced by processes such as the reaction of isobutylene and methanol contains small but significant amounts of impurities including water, methanol, acetone, methyl ethyl ketone, tertiary butyl alcohol and the like. In certain applications the presence of such impurities causes problems with respect to the desired use. It is desirable to provide a process by which the impurities can be conveniently separated.
It is known that the close boiling oxygenated impurities can be separated to a significant degree from MTBE by an elaborate and extensive distillation procedure. However, such procedures are costly and time consuming, involving as they do substantial capitol investments and utilities expenses.
U.S. Pat. No. 5,401,887 shows treatment of ethyl tertiary butyl ether (ETBE) formed by reaction of isobutylene and ethanol and containing ethanol with zeolite 13X in order to remove ethanol. However, according to related U.S. Pat. No. 5,621,150 tertiary butyl alcohol (TBA) is not separated by the adsorptive treatment but remains with the ETBE.
U.S. Pat. No. 4,605,787 shows separation of methanol from MTBE and TBA by contact with a small pore zeolite. Example 19 demonstrates that TBA is not separated.
In many instances it is distinctly advantageous to separate from MTBE both the contained methanol and the contained TBA and the present invention provides such a procedure.
U.S. Pat. No. 6,417,412 shows the separation of various impurities from TBA by contact with a large pore zeolite such as 13X in the sodium form.
It is desirable to have a simplified procedure whereby MTBE process streams can be conveniently treated to separate close boiling impurities including methanol and TBA by a relatively simple and straight forward procedure.